Self-pressurizing supraglottic airway

ABSTRACT

A supraglottic airway of the type used to facilitate lung ventilation and the insertion of endo-tracheal tubes or related medical instruments through a patient&#39;s laryngeal opening where the shield is designed to have an internal increase in pressure during assisted inhalation such as positive-pressure ventilation.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of U.S. Utility patent applicationSer. No. 11/747,486, filed May 11, 2007 now U.S. Pat. No. 7,934,502, theentire disclosure of which is herein incorporated by reference.

BACKGROUND

1. Field of the Invention

The invention relates to an artificial airway device, more specificallyto a supraglottic airway designed to have increased internal pressureduring introduction of artificial positive-pressure ventilation.

2. Description of the Related Art

In general, supraglottic airways such as laryngeal masks allowing forboth rapid lung ventilation and the insertion of medical instruments andtubes into the laryngeal openings of patients have been described inpatents, such as U.S. Pat. No. 4,509,514 to Brain and U.S. Pat. Nos.6,422,239 and 5,937,860 to Cook the entire disclosures of which wereherein incorporated by reference. Laryngeal masks generally consist oftwo major components, a breathing tube and an inflatable or rigidshield, these devices are inserted into a patient's throat, and whenproperly positioned, cover the laryngeal opening. A seal is then formedaround the circumference of the laryngeal opening by the inflation of aring-like structure located toward the front of the mask (patient end).Inflation of the ring exerts pressure against the front, sides, and rearportions of the oropharynx, securing the device in place such that thelaryngeal opening is positioned in alignment with a recessed cavity inthe mask face. Alternatively, the structure of the shield may be formedas a large semi-rigid plastic construct which generally serves to sealby contouring to the shape of the throat and imparting pressure on thethroat by its own size and shape effectively filing available space.

Extending from a point external to the oral cavity, the flexiblebreathing tube terminates within the recessed cavity, aligned axiallywith the laryngeal opening. The positioning of the flexible breathingtube allows the passage of endo-tracheal tubes or related medicalinstruments into the laryngeal opening, in addition to allowing forpositive-pressure lung ventilation.

While current supraglottic airways such as laryngeal masks can providefor improved placement and breathing over a traditional endotrachealtube, they can be improved. In particular, the use of inflatedstructures or semi-rigid plastic constructs to hold the device in placein the throat can lead to undesirable pressure on throat tissue. Currentdesigns seal the laryngeal opening inside the recess by exerting aconstant pressure on surrounding tissue effectively forcing thestructure of the mask into the walls of the throat while it is in place.This constant pressure is generally not relieved until the device isremoved. While the structure of these devices are generally made pliableand soft so as to minimize potential damage from their near constantcontact with throat tissues, the constant pressure they impart onpotentially sensitive structures in the throat can, in some cases, leadto tissue fatigue and damage.

The problem is exacerbated by the fact that the person inserting theairway generally has little to no control on the pressure exerted by theairway and often has no indication thereof. Thus, the device can easilybe accidentally over-inflated or over-sized exerting more pressure thanis necessary or desirable on the tissue of the throat, often withoutrealizing it.

SUMMARY

The following is a summary of the invention in order to provide a basicunderstanding of some aspects of the invention. This summary is notintended to identify key or critical elements of the invention or todelineate the scope of the invention. The sole purpose of this sectionis to present some concepts of the invention in a simplified form as aprelude to the more detailed description that is presented later.

Because of these and other problems in the art, described herein is asupraglottic airway primarily intended to facilitate lung ventilationand the insertion of endo-tracheal tubes or related medical instrumentsinto a patient's trachea as needed during general anesthesia, intensivecare, critical patient care, or at any other time that ventilation wouldbe desired. In an embodiment of such a supraglottic airway, the airwaycomprises a flexible ventilation tube and a positioning shield which ischaracterized as being “self-pressurizing.” This term refers to the factthat the shield generally imparts an increased sealing pressure on thethroat when under positive pressure from assisted ventilation than itdoes during spontaneous exhalation. In this way the shield is generallyonly “pressurized” intermittently and only exerts its highest sealingpressure on throat tissues in a limited fashion. The shield generallyconforms to the anatomy of the oropharynx region surrounding thelaryngeal opening, and is securely affixed to the distal end of theventilation tube.

Described herein, among other things is a supraglottic airwaycomprising; a respiratory tube having a distal end, a proximal end, anda length therebetween, the respiratory tube having a hollow interior;and a shield comprising a posterior base and a sealing ring surroundingthe posterior base and defining an inner volume within the sealing ringand a cavity above the posterior base; wherein the shield is attached tothe distal end of the respiratory tube so that the hollow interior ofthe respiratory tube is in fluid communication with the cavity; whereinthe hollow interior and the cavity jointly define an air path; andwherein the inner volume of the sealing ring is capable of fluidcommunication with the air path.

In an embodiment of the airway the respiratory tube is smoothly curvedand may comprise a connector removeably attached to the proximal end ofthe respiratory tube.

The airway may be constructed using any technique of manufacture suchas, but not limited to, blow-molding or injection molding. The airwaymay be intended to be disposable, that is for single use, or may beintended for sterilization and reuse between patients.

In an embodiment of the airway the air path may be in fluidcommunication with the inner volume via a port. This port may be locatedin the respiratory tube in a side of the sealing ring opening into thecavity and may comprise a single hole, multiple holes, or an elongated,potentially continuous, slit which may circumscribe the cavity.

There is also described herein a supraglottic airway comprising; arespiratory tube having a distal end, a proximal end, and a lengththerebetween, the respiratory tube defining an air path therethrough;and a shield comprising a posterior base and a sealing ring surroundingthe posterior base and defining an inner volume within the sealing ringand a cavity above the posterior base, wherein the shield is attached tothe distal end of the respiratory tube so that the air path in therespiratory tube is in fluid communication with the cavity and whereinthe cavity is in fluid communication with an inner volume of the sealingring.

There is also described herein, a supraglottic airway comprising; arespiratory tube having a distal end, a proximal end, and a lengththerebetween, the respiratory tube defining an air path therethrough;and a shield comprising a posterior base and a sealing ring surroundingthe posterior base and defining an inner volume within the sealing ring,wherein the shield is attached to the distal end of the respiratory tubeso that the air path in the respiratory tube is in fluid communicationwith the inner volume of the sealing ring.

There is also described herein a method of providing an artificialairway to a human comprising: placing in the throat of a human, asupraglottic airway comprising; a respiratory tube having a distal end,a proximal end, and a length therebetween, the respiratory tube defininga hollow interior; and a shield comprising a posterior base and asealing ring surrounding the posterior base and defining an inner volumewithin the sealing ring and a cavity above the posterior base, whereinthe shield is attached to the distal end of the respiratory tube and thecavity and the hollow interior jointly define an air path; attaching theproximal end to a ventilation apparatus; and forcing air into the airpath to provide air to the patient; wherein, the act of forcing air intothe air path alters the pressure in the inner volume of the sealingring.

Depending on the embodiment of the method the alteration of pressure inthe inner volume of the sealing ring may alter the size of the sealingring as air is forced into the air path, increase the strength of sealof the sealing ring to the throat or increase the pressure the sealingring imparts on the throat.

There is still further described herein, an artificial breathing systemcomprising: a supraglottic airway including; a respiratory tube having adistal end, a proximal end, and a length therebetween, the respiratorytube defining a hollow interior therethrough; and a shield comprising aposterior base and a sealing ring surrounding the posterior base anddefining an inner volume within the sealing ring and a cavity above theposterior base, wherein the shield is attached to the distal end of therespiratory tube and the cavity and the hollow interior jointly definean air path; and a ventilation apparatus designed to increase pressurein the air path which is attached to the proximal end; wherein, when theventilation apparatus increases pressure in the air path it also altersthe pressure in the inner volume in the sealing ring.

Depending on the embodiment of the system the alteration of pressure inthe inner volume of the sealing ring may alter the size of the sealingring as air is forced into the air path, increase the strength of sealof the sealing ring to the throat or increase the pressure the sealingring imparts on the throat.

In an embodiment of the system, there is a port interconnecting theinner volume of the sealing ring to at least one of the cavity or thehollow interior, the port allowing the alteration in the pressure of thesealing ring. This port may be located in the respiratory tube in a sideof the sealing ring opening into the cavity and may comprise a singlehole, multiple holes, or an elongated, potentially continuous, slitwhich may circumscribe the cavity.

There is still further described herein, a supraglottic airwaycomprising; a respiratory tube having a distal end, a proximal end, anda length therebetween, the respiratory tube having a hollow interior; ashield comprising a posterior base and a sealing ring surrounding theposterior base and defining a cavity above the posterior base; and meansfor allowing fluid communication between an inner volume of the sealingring and at least one of the cavity or the hollow interior of therespiratory tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an embodiment of a self-pressurizinglaryngeal mask as assembled.

FIG. 2 shows a partially exploded view of the embodiment of FIG. 1 toshow a manner of assembly.

FIG. 3 shows a perspective view of a shield.

FIG. 4 shows a perspective view of a breathing tube.

FIG. 5 shows a cut-through along line 5-5 in FIG. 3.

FIG. 6 shows a perspective view of another embodiment of aself-pressurizing laryngeal mask as assembled.

FIG. 7 shows a perspective view of another embodiment of a shield

FIG. 8 shows a cut-through along line 8-8 in FIG. 7

FIG. 9 shows a shape of the shield of FIG. 7 when there is no airflowinto the hollow interior of the sealing ring and expansion from suchflow.

FIG. 10 shows an embodiment of a laryngeal mask in place in the throatof a patient.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The following detailed description illustrates by way of example and notby way of limitation. Described herein, among other things, is anembodiment of a supraglottic airway which includes a shield for sealingwith the larynx which is designed to exert greater pressure, andtherefore a stronger seal, when an assisted inhalation is being providedfor the patient during positive-pressure ventilation. Specifically, thesupraglottic airway has a shield (201) including a sealing ring (401).The ring (401) is in gaseous (or more generally fluid) communicationwith the airway path through which artificial respiration air isprovided to the patient. While the supraglottic airway described hereinincorporates certain features in the shape and arrangement of the shield(201) for improved placement in the airway, it should be recognized thatthese features are not required and the sealing rings (401) and relatedstructures discussed herein can be used on airways of other shapes andforms.

FIG. 1 provides for an embodiment of a supraglottic airway (100) in theform of removable laryngeal mask airway. This mask is chosen as anexemplary form of supraglottic airway (100) including aself-pressurizing sealing ring (401). It is in no way intended to bedescriptive of all airways upon which a self-pressurizing sealing ring(401) may be used in other embodiments.

In the depicted embodiment of FIG. 1 the airway (100) generallycomprises two major components. There is a respiratory tube (205)generally formed into an arcuate curve and a positioning shield (201)which is secured toward the distal end (203) of the respiratory tube(205). The airway (100) is generally composed of a relatively softflexible material such as, but not limited to, silicone-rubber polymeror plastics.

The positioning shield (201) comprises a generally wedge-shaped flexiblesealing ring (401) with a pliable molded posterior base (403) attachedthereto so that the posterior base (403) forms the base of, and thesealing ring (401) generally surrounds, a cavity (511). The sealing ring(401) is also generally sized and shaped to generally conform to theapproximate available space in the oropharynx region without significantdistortion or causing significant displacement of throat surfaces.Depending on embodiment, the sealing ring (401) may comprise a number ofdifferent structures and may be ellipsoidal, toroidal, or of similarshape. As shown in FIG. 5, the sealing ring (401) also generallyincludes an inner volume (412), which may be generally sealed, or moreopen, depending on embodiment.

The posterior base (403) is secured longitudinally within a space in thecenter of the sealing ring (401) to form cavity (511). The posteriorbase (403) is generally attached in a fashion to form an elongated andtapered hemisphere relative the generally major plane of the sealingring (401) so as to give the shield (201) an overall shape such as thatseen in the FIGS. In the depicted embodiment, there are semi-rigidraised ridges (409) positioned longitudinally parallel to each otheralong the surface (413) of the posterior base (403) “inside” the spaceof the sealing ring (401). This space above the posterior base (403) and“inside” the sealing ring (401) is defined herein as a cavity (511).

The sealing ring (401) may comprise a number of different shapes orstructures but will generally comprise a section extending upward fromthe posterior base (403) so as to form the cavity (511) in the shield(201). The sealing ring (401) is generally constructed of a flexiblematerial which is capable of being moved when placed under the influenceof air pressure on the order of that expected during positive-pressureventilation of a patient. This movement will be characterized asexpansion, which may comprise inflation such as in a balloon, or may bea shifting or movement of various structures to have a generally largerdisplacement. An embodiment of the expansion of a sealing ring (401) isshown in FIG. 9 and generally provides the expected type of flexibilitywhen internally exposed to increased pressure.

In the embodiments of FIGS. 1-6, the sealing ring (401) comprises a ringshape which is itself hollow and encloses a generally hollow innervolume (412) as well as forming the cavity (511). In the embodiment ofFIGS. 7-8, the sealing ring (401) comprises a hollow channel which hasbeen formed into a ring shape. Generally, the sealing ring (401) isdesignated as having an exterior side (673) and an upper surface (675)which bends generally inward toward the center of the posterior base(403) from the exterior side (673). The upper surface (675) may then beconnected to an inner side (677) which is directed back down and towardthe surface of the posterior base (403). Depending on embodiment, theinner side (677) may attach to the posterior base (403) so as to providethe sealing ring (401) with the tube-like structure discussed inconjunction with FIGS. 1-6 or may not providing a more channel-likestructure as discussed in conjunction with FIGS. 7 and 8. FIGS. 1, 5 and6 provide for perspective and cut-through drawings of shields which aremore tubular, while FIGS. 7-8, which show the inner side (677) extendinga predetermined distance toward the posterior base (403) before ending,show the inner side (677) being suspended above the posterior base(403).

The shield (201) in the depicted embodiment of FIG. 1, is connected tothe respiratory tube (205) by means of a hollow wedge (501) which allowsthe air pathway defined within the respiratory tube (205) to passthrough the shield (201) and into the cavity (511) formed above theposterior base (403) and inside the recess of the sealing ring (401). Ina preferred assembly, the hollow wedge (501) is attached generally tothe distal end (203) of the respiratory tube (205) as is visible in FIG.4 and comprises a somewhat more rigid construction than the othercomponents. The wedge section may be inserted into the end of therespiratory tube (205), or may be co-molded with the respiratory tube(205) and/or shield (201) in alternative embodiments. The wedge sectionmay include the wedge (501) as well as a raised disk (553) to beutilized in connection to the shield (201) if those parts are notco-molded. In the event that the airway (100) is molded as a singlepiece, such disk (553) is clearly unnecessary. In still furtherembodiments the wedge (501) may be modified in shape from that depictedor may be completely eliminated providing for a connection with analternative shape to the connection between the respiratory tube (205)and the shield (201) depicted in the FIGS. In the embodiment of FIG. 1,the respiratory tube (205) passes through a first peripheral seal (703)to exit the cavity (511). This first seal will generally be an airtightseal, but that is by no means required. There is a second peripheralseal (705) towards the proximal end (505) of the inflatable positioningshield (201) which generally provides an airtight seal isolating the airregion internal to the cavity (511) and/or internal to the respiratorytube (403) from the air region outside the shield (201) should thecavity (511) and proximal end (207) of the respiratory tube (205) besealed. This sealing will be discussed later in more detail.

The wedge (501) therefore gives an access into the cavity (511) from theinterior of the respiratory tube (205) allowing air to pass from thecavity (511) into the distal end (203) of the respiratory tube (205) andfrom there out the proximal end (207) of the respiratory tube (205) orvice-versa. The wedge (501) is generally formed into an angle (521) tothe length of the respiratory tube (205) which is generally between 0and 90 degrees and preferably about 30 to about 35 degrees with theposterior base (403), forming an elongated elliptically shaped distallumen (523) open to the interior of the cavity (511) and interior of therespiratory tube (205).

There may also be included a ventilation lumen (531) through the wedge(501) to provide an alternate airway passage in the event the distallumen (523) becomes obstructed during patient lung ventilation. Theventilation lumen (531) also generally prevents the formation of apressure differential between the cavity (511) and flexible respiratorytube (205). Absent a pressure differential, any object obstructing thedistal lumen (523) will not generally become inextricably lodged.

In order to provide that air introduced into the airway (100) for use bythe patient be able to pressurize the sealing ring (401), there isprovided a fluid communication port (452) which allows for fluid(particularly gas in the form of ventilated air) to pass from the airpath to the interior of the sealing ring (401). This fluid communicationport (452) may be located anywhere in the air path providing access tothe inner volume (412) of the sealing ring (401). In the embodiment ofFIG. 1 the port (452) is located near the distal end of the respiratorytube (205) providing fluid flow from the respiratory tube (205) to theinner volume (412) of the sealing ring (401). In the embodiment of FIG.6, the port (452) comprises two holes located in the interior surface(677) of the sealing ring (401) providing fluid flow from the cavity(511) to the inner volume (412) of the sealing ring (401). In theembodiment of FIG. 8, the port (452) is an elongated generallycontinuous slit in the interior surface (677) which circumscribes thecavity (511). While these examples provide some embodiments, other fluidcommunication ports (452) may be used in other embodiments.

The respiratory tube (205) may be formed in any manner known to those ofordinary skill in the art but will generally form a smoothly curvinghollow cylinder of generally circular or elliptical cross-sectionpreferably approximating, for ease of insertion, the shape of the humanthroat. The respiratory tube (205) is preferably sized and shaped toaccommodate the passage of endo-tracheal tubes and related medicaldevices up to 9 French in diameter. The length of respiratory tube (205)is such that when the laryngeal mask (100) is properly positioned foruse within the oropharynx, the attachment (proximal) end (207) ofrespiratory tube (205) is located exterior to the oral cavity of thepatient. The attachment end (207) of the respiratory tube (205)terminates in an unobstructed proximal lumen (209), providing a directpathway through the respiratory tube (205) to the distal end (203) anddistal lumen (523). In alternative embodiments, the attachment end (207)may be fitted with removable adapters or connectors (871) suitable forconnection to a variety of medical devices, for example, lungventilation machines.

As shown in FIG. 10, when the airway (100) is in place in a patientthere is provided by the structure of the airway (100) an air flowpassageway (454) for air to flow from external to the patient into thepatient's lungs to provide for ventilation of the patient. This air flowgenerally comprises air passing into the attachment end (207) of therespiratory tube (205) from a ventilation apparatus, such as the squeezebag (951) depicted in FIG. 9, or from a mechanical ventilator. That airthen flows through the respiratory tube (205) and generally into thecavity (511) of the shield (201). As the shield (201) is over thelaryngeal opening (941), which may be held open by the presence of thewedge (501), the air is then directed, at least in part, into thepatient's lungs.

FIG. 10 shows how the sealing ring (401) and shield (201) are pushedagainst the surface of the throat (945) when air pressure inside the airpath (454) from the attachment end (207) of the respiratory tube (205)to the patient's trachea (943) is increased. This occurrence is called“self-pressurizing” as the sealing ring (401) inflates, pressurizes, orotherwise adjusts using air being provided to the patient, instead ofair separately provided to the sealing ring (401) through a separateinflation bulb or related device. Self-pressurization generally providesfor increased sealing pressure of the shield (201) in the throat (945)during assisted inhalation. The pressure is due to expansion or otheralteration of the sealing ring (401) as air in the respiratory pathway(454) (provided under a positive pressure to provide forpositive-pressure ventilation of the patient) is able to pass throughthe communication port (452) and into the inner volume (412) of thesealing ring (401). Essentially, the expansion or alteration occurs asair forced into the lungs of the patient from an external source is alsodirected through the communication port (452) and into the inner volume(412) of the sealing ring (401). During positive-pressure ventilation,the ventilation apparatus will begin by forcing air from the squeeze bag(951) or similar device, through the connector (871) and into therespiratory tube (205). It will then flow into the cavity (511) via thedistal end (203) of the respiratory tube (205). An increase in the airpressure inside the cavity (511) or tube (205) will also result in asimultaneous increase in air pressure within the sealing ring (401) andpushing of the structure of the sealing ring (401) into the structure ofthe throat (945) due to air passing through the communication port (452)and into the inner volume (412) of the sealing ring (401).

The sealing is best understood in conjunction with FIGS. 9 and 10. Whilethe below discussion is believed to be a course of operation of thedevice, this is in no way intended to limit the invention to anyparticular theory of operation. When in place in the throat (945), thesealing ring (401) is generally in at least partial contact with thesurface (953) of the throat (945) adjacent to or about the laryngealopening (941). At this point the tissue pressure between the throat andairway (100) is generally reduced. This contact serves to define an airarea comprising the cavity (511) which generally only has preparedaccess points being the laryngeal opening (941) and the respiratory tube(205). The seal between the sealing ring (401) and the surface (953) mayor may not be complete, but is expected to be relatively complete in anembodiment of the inflation. As air is forced into the respiratory tube(205), the air pressure inside the respiratory tube (205) and the cavity(511) increases. This increase will push in all directions internal tothe cavity (511) and will attempt to push the shield (201) away from thelaryngeal opening (941). However, as the sealing ring (401) is flexible,air pressure on the upper surface (675) from air passing into the innervolume (412) will generally push the upper surface (675) toward thesurface (953) of the throat (945) it is in partial contact with asillustrated by the arrows in FIG. 9. This will result in an increasedconnection pressure between the shield (201) and the throat (945).Further, as the pressure pushes the airway (100) away from the laryngealopening (941) it will also generally push the posterior base (403) intothe back of the throat further increasing the pressure.

The example of expansion shown in FIG. 9 illustrates an initial positionof the sealing ring (401) in dashed line with the expanded position insolid line. The expansion occurs because the air pressure internal tothe cavity will increase relative to the air pressure outside the shieldduring positive-pressure ventilation (201) as indicated by the arrows.As the sealing ring (401) is generally constructed of flexible materialand fluid communication is allowed between the air path (454) and theinner volume (412) of the sealing ring (401), the material will move inresponse to the increased pressure increasing connection pressure to thethroat (945). It should be apparent that while the air can flow into theinner volume (412) of the sealing ring (401) from a port (452) openinginto the cavity (511), the port (452) can be positioned in otherlocations to allow such fluid communication. One such alternative isshown in FIG. 1 where the port (452) is between the respiratory tube(205) and the sealing ring (401).

As the seal pressure increases, so does the ability of the shield (201)to maintain the internal airflow from the ventilation apparatusdirecting additional air into the lungs of the patient. Once the lungshave been appropriately inflated, exhalation generally occurs by havingthe patient spontaneously breath out. Air escaping the patient's lungswill generally pass back from the lungs through the respiratory tube(205) and escape the patient. During exhalation, however, it isgenerally not necessary that the shield (201) be tightly sealed. If airwas to escape the shield (201) by going around it, this air would stillgenerally pass out of the mouth of the patient.

By allowing the shield (201) to self-pressurize when air pressure insidethe airway (100) is increased by air being forced into the patient'slungs during assisted inhalation, and a decrease of the pressure duringexhalation, the airway (100) significantly reduces the pressure placedon the throat (945) during the course of use of the airway (100). Inparticular, it is understood in the art that generally exhalation takestwice as long as inhalation, therefore the time that the throat issubject to the increased sealing pressure from the pressurized shield(201) is generally reduced by about two-thirds since the airway (100) ispressurized an increased amount only during inhalation. This cansignificantly reduce the potential for damage to pressure sensitivestructures in the throat by simply reducing the amount of time, in anyprocedure, the structures are exposed to the increased pressure.

Further, the self-pressurization provides for some controlled monitoringof the pressure placed on the structures in the throat contacted by theshield (201). It is understood that when pressurizing the lungs of apatient during assisted inhalation, peak pressures should generally notbe maintained above the range of about 60 cm of water as this can resultin damage to the lungs. Pressures are generally maintained in the 15 to30 cm of water range. For this reason, squeeze bags and otherventilation systems are generally inhibited from producing damagingpressure by their design and/or operation. It is also generally theunderstanding of the art that similar pressure ranges to those which aresafe for lung inflation are also within a safe zone for inhibitingdamage to throat structures. As the pressure inside the shield (201) iseffectively limited to the maximum pressure provided by the attachedventilation apparatus, and since the ventilation apparatus is providedwith a safe zone for lung ventilation which is believed inside the safezone for throat damage, both body structures are simultaneouslyprotected.

As should be apparent from the above discussion, the self-pressurizationof the sealing ring (401) occurs by having the sealing ring (401) be influid communication with the air path (454) in such a fashion that whenair is directed into the air path (454), there is an air pressuredifferential created inside the shield (201) which allows air to flowinto inner volume (412) of the sealing ring (401) providing forpressurization of the flexible structures of the sealing ring (401) toexpand and increase the contact pressure between the throat and thesealing ring (401).

In the embodiment of FIG. 1, communication is achieved by the presenceof port (452) located in the respiratory tube (205) which directs air toan inner volume (412) of the sealing ring (401). This port (452) may beof any shape, size or arrangement but will generally be of sufficientsize so as to allow free air communication between the air space insidethe respiratory tube (205) and the space at least partially internal tothe surface comprising the sealing ring (401). That is, air flow fromthe respiratory tube (205) can pass into the inner volume (412) of thesealing ring (401) without major interference from surface effects orthe like. In the alternative embodiment of FIG. 6, the sealing ring(401) includes a port (452) which is a series of holes allowing fluidcommunication from the cavity (511) to the inner volume (412) of thesealing ring (401). The embodiment of FIG. 8 provides for a morecontinuous port (452) which is a slit around the inner side (677) of thesealing ring (401). These different embodiments still provide for thesame net result. Air which is present inside the air path (454) is ableto flow into the sealing ring (401).

One of ordinary skill in the art would see that the three depictedembodiments are not the only possible structures which would allow forfluid communication from the air path to the sealing ring (401). In anadditional alternative embodiment, the port (452) could be replaced byalternative structures allowing fluid communication.

The airway (100), in an embodiment, may be constructed from a singleblow-molded or injection molded construction which is formed into boththe shield (201) and respiratory tube (205) by blowing or injectingsuitable construction materials such as plastics or silicone into ashaped die. In such an embodiment, the entire airway (100) may be formedas a single piece. Often to facilitate such construction, theventilation lumen (531) and distal lumen (533) would be sealed in theinitial formation. The lumens (531) and (533) would then be punched orcut out from resultant structure to create the openings. The embodimentof FIG. 1 would generally be suitable for such single piece blow-moldingconstruction. Alternatively, the airway (100) can be formed from aplurality of separately constructed pieces which are later connectedtogether.

Blow-molding techniques generally require that the structure to beformed comprise a hollow balloon which is then pushed or molded intoshape. FIG. 5 shows a cross-section of the shield of FIG. 3 indicatinghow the shield (201) is preferably constructed and how the balloon iscompressed and formed into the desired structure shown in FIG. 3. As canbe seen in FIG. 5, the sealing ring (401) and posterior base (403) areformed by taking the opposing sides of the balloon and partially pushingthem together at an interior location so that they touch at a pointspaced from the entry point (462) and the neck (508). These opposingsides are then adhered together either through the use of an adhesive orsimply through the adhesive capabilities of the material being formed soas to form the posterior base (403) and sealing ring (401) as shown inthe FIGS. As should be apparent, this style of formation results in astructure whereby the sealing ring (401) forms a generally toroidalstructure including an inner volume (412) as discussed in conjunctionwith FIG. 1, and the posterior base (403) does not allow for air passagebetween the two surfaces which form its upper (402) and lower (404)portions thereby forming a generally solid base attached to the sealingring (401) and resulting in the “dish” shape of FIG. 3.

As can be further seen in FIG. 5, the posterior base (403) is thickerthan either of the outer surfaces (410) of the sealing ring (401) whichprovides additional strength to the shield (201) as a whole. At the sametime, however, the structure is not rigid and is capable of bendingduring insertion. In a preferred embodiment, the outer surfaces (410)are in fact molded to be significantly thinner than each of the upperportion (402) and lower portion (404) to provide for even more strengthto the posterior base (403) and to provide for improved mold flowcharacteristics.

In an embodiment where the airway (100) is comprised of two pieces, inorder to assemble the embodiment of airway (100) shown in FIG. 1, it isgenerally preferred that the following steps be performed to assemblethe components, generally as indicated in FIG. 2. First the componentsare formed as shown in FIGS. 3 and 4. The shield (201) has a hole (709)cut through the proximal wall of the cavity (511). As should be apparentfrom FIGS. 3 and 5, the entry point (462) and hole (709) thereforepresent a relatively straight passage which extends from inside thecavity (511) through the sealing ring (401) and out the proximal end(505). There is also generally formed a connection recess (435) in theposterior base (403). This may be cut out or may be formed by simplecompression of the material forming the posterior base (403).

The respiratory tube (205) is now inserted, proximal end (207) first,through the hole (709), passed through the sealing ring (401), andextended out the entry point (462) and thus the posterior end (505) ofthe shield (201). The hole (709) and entry point (462) are preferablysized and shaped to be of relatively similar size to the exteriordiameter of the respiratory tube (205) so that a tight connection isformed by the respiratory tube (205) distending the material of theshield (201) slightly in both places. The respiratory tube (205) willcontinue to be slid through the hole (709) and entry point (462) untilthe hole (709) interacts with the groove (551) and disk (553). At thatpoint, the wedge (501) and disk (553) will generally be the onlyportions of the respiratory tube (205) which has not passed through thehole (709), the reinforced support (525) will be adjacent to the recess(435) in the posterior base (403), and the fluid communication port(452) is internal to the sealing ring (401) allowing air in therespiratory tube (205) to flow into the sealing ring (401). These pieceswill then be connected together resulting in the wedge (501) beingpositioned in the cavity (511) and generally flush with the interior ofthe posterior base (403). The connection between the posterior base(403) and the reinforced support (525) may be formed in any manner knownto one of ordinary skill in the art, however, in a preferred embodiment,the two devices are adhered together with a generally non-separableadhesive. The respiratory tube (205) now is arranged to generally passthrough the sealing ring (401) allowing air flow from the respiratorytube (205) into both the interior of the sealing ring (401) and thecavity (511).

In the depicted embodiment, the disk (553) and groove (551) formedtoward the distal end (203) of the respiratory tube (205) serve toreinforce the connection (703). In particular, the material surroundingthe hole (709) will end up being stretched by the passing of therespiratory tube (205) until the hole (709) is aligned with the groove(551). The material will then relax and the hole (709) will collapseslightly into the groove (551). This provides a first level of support.The disk (553) adjacent to the hole (709) can then be provided with anadhesive which adheres to the shield (201).

While in the above embodiment, as depicted in FIG. 2, the proximal end(207) of the respiratory tube is first threaded through the hole (703)and entry point (462), in an alternative embodiment, the wedge (501) andrespiratory tube (403) may actually be inserted in the opposingdirection to the embodiment shown in FIG. 2. In this alternativeembodiment, the wedge section and the distal end (203) of therespiratory tube (205) would be first inserted through the entry point(462), run through the sealing ring (401), and exit the hole (703).While this method is viable in most cases, it is generally not preferredas it is usually more difficult to perform. Further, in someembodiments, it may require redesign of the wedge section components(such as the wedge (501), disk (553), or reinforced support (525)), toprevent damage to the hole (703) and entry point (462) during the wedge(501) passing through those structures.

Generally, use of the airway (100) would proceed as follows. Beforeinsertion, the sealing ring (401) would be in a neutral position,generally at an ambient internal pressure, and there would be little orno positive pressure created within the air path (454). The mouth of thepatient is opened and their head positioned for insertion of the airway(100). The shield (201) is pushed into the orolaryngeal region. Thesmooth arcuate curves of the combined respiratory tube (205) and shield(201) positions the laryngeal mask (100) in alignment with the laryngealopening (741). Upon proper positioning, as generally determined by aresistance to further forward motion, the airway (100) is consideredplaced. A breathing device or machine, such as a ventilator or a squeezebag (951) would then be coupled to the attachment end (207) of therespiratory tube (205).

Positioned within the cavity (511), the distal lumen (523) is axiallyaligned with the laryngeal opening (941), permitting positive-pressurelung ventilation to be performed through the airway (100), or allowingendo-tracheal tubes or related medical instruments inserted through therespiratory tube (205) to exit through the distal lumen (523) which isdirectly aligned for passage into the laryngeal opening (941). Removalof the airway (100) is normally the reverse of the insertion proceduredescribed above. As the device is generally relatively inexpensive tomanufacture, once it has been removed the airway (100) will generally bediscarded. However, in an alternative embodiment it may be sterilizedand reused in any manner understood by those of ordinary skill in theart.

During assisted positive-pressure ventilation, the airway (100) wouldoperate as follows. When a breath is provided for the patient, theventilator or other device would be used to increase air pressure insidethe respiratory tube (205) forcing air into the tube (205) and towardthe cavity (511). As the air pressure increases along the tube (205)and/or cavity (511), some of the air being pressed toward the patientwill enter the port (452) and flow into the sealing ring (401), whileother air will continue to flow out the wedge (501) and into the cavity(511) and the trachea (943) and lungs of the patient. The pressure ofair flowing into the lungs, and the pressure of air flowing into thesealing ring (401) will generally be relatively equal. As there isgenerally no external escape for the air in the air path, the sealingring (401) will generally pressurize causing it to seal tighter withinthe throat (945). This will force the airway (100) into stronger contactwith the walls of the throat (945) and surface (951). As the shield(201) and throat (945) are pressed together, they will form a strongerseal and will inhibit air from inside the cavity (511) from passingbetween them, instead directing that air into the lungs of the patient.This process will continue as long as air is under positive pressure anddirected toward the lungs by the ventilation apparatus.

Once the inhalation is complete, the pressure will generally bedecreased inside the air path (454). This will result in the pressure inthe air path (454) decreasing back toward ambient and the sealing ring(401) decreasing the pressure imparted by the airway (100) to the throat(945). As the patient begins to exhale (generally by spontaneousexhalation), the patient will push air back toward the airway (100).This air will generally pass into the cavity (511) and then flow outinto the respiratory tube (205) and escape the patient's body. Some ofsuch air may pass into the sealing ring (401) and serve to increase thepressure slightly, but this will generally result in a pressure betweenthe sealing ring (401) and the throat (945) still being significantlyless than that during the assisted inhalation Alternatively, some airmay escape around the edges of the shield (201). As the pressure ofspontaneous exhalation is generally insufficient to result in opening ofthe esophageal sphincter, this air will generally escape around theairway (100) and exit the patient through their mouth or nose. Onceexhalation is complete, the process will generally repeat beginning withanother inhalation.

The elimination of the need to tightly seal the shield (201) duringexhalation with as much pressure as during inhalation relates in part tothe expected behavior of air during inhalation and exhalation. It isundesirable for air, during forced inhalation to be able to proceed downthe esophagus. At sufficient pressure to inflate the lungs there is alsogenerally sufficient pressure to open the esophageal sphincter and allowair to enter into the stomach. Forcing air into the stomach can create apotentially dangerous situation. Therefore, during this forcedinhalation, it is desirable that the shield (201) seal strongly so as toprovide an air passage into the laryngeal opening (941) without allowingthe pressurized input air to escape into the stomach. The airway (100)carries out this task since the tightness and inflation of the sealingring (401) to the throat (945) increases proportionate to the force ofair within the passageway. As the air pressure increases in thepassageway (approaching levels where air could be forced in thestomach), the sealing ring (401) inflates and improves the tightness ofits seal to the throat (945), inhibiting air from passing outside of theair passage and directing that air into the lungs.

During spontaneous exhalation, the pressure produced by the patient'slungs is generally insufficient to force air past the esophagealsphincter, and thus there is a decreased need for the airway (100) to betightly sealed to the laryngeal opening (941). While it is expected thatmost air will in fact flow out the respiratory tube (205) as the path ofleast resistance, even if it does not, the air which escapes will haveinsufficient force to push past the esophageal sphincter and willinstead escape around the airway (100) and out the mouth or nose as innormal breathing.

While the invention has been disclosed in connection with certainpreferred embodiments, this should not be taken as a limitation to allof the provided details. Modifications and variations of the describedembodiments may be made without departing from the spirit and scope ofthe invention, and other embodiments should be understood to beencompassed in the present disclosure as would be understood by those ofordinary skill in the art.

The invention claimed is:
 1. A supraglottic airway comprising; arespiratory tube having a distal end, a proximal end, and a lengththerebetween, said respiratory tube having a hollow interior; and ashield comprising a posterior base and defining a cavity within theshield above the posterior base, and a sealing ring surrounding saidposterior base, said sealing ring having a cross-section defining aclosed curve, said closed curve cross section extending substantiallyaround said posterior base, said sealing ring being substantiallyenclosed from said cavity and defining an inner volume within saidsealing ring apart from said cavity with said respiratory tube hollowinterior and sealing ring being in fluid communication in a manner toenable said sealing ring to inflate when a pressure in said respiratorytube hollow interior is greater than in said sealing ring inner volumeand enabling said sealing ring to deflate when a pressure in saidrespiratory tube hollow interior is lower than in said sealing ringinner volume; wherein said shield is attached to said distal end of saidrespiratory tube so that said hollow interior of said respiratory tubeis in fluid communication with said cavity; and wherein said hollowinterior and said cavity jointly define an air path.
 2. The airway ofclaim 1 wherein said respiratory tube is smoothly curved.
 3. The airwayof claim 1 wherein said shield is formed by blow-molding.
 4. The airwayof claim 1 wherein said shield formed by injection molding.
 5. Theairway of claim 1 wherein said air path is in fluid communication withsaid inner volume via a port.
 6. The airway of claim 5 wherein said portcomprises multiple holes.
 7. The airway of claim 5 wherein said portcomprises an elongated slit.
 8. The airway of claim 5 wherein said portis located in a side of said sealing ring opening into said cavity. 9.The airway of claim 8 wherein said port comprises multiple holes. 10.The airway of claim 8 wherein said port comprises an elongated slit. 11.The airway of claim 1, wherein said sealing ring is inflatable at a ratedifferent from other parts of said shield when positive pressure isintroduced in said shield.
 12. A supraglottic airway comprising; arespiratory tube having a distal end, a proximal end, and a lengththerebetween, said respiratory tube defining an air path therethrough;and a shield comprising a posterior base and defining a cavity withinthe shield above the posterior base, and a sealing ring surrounding saidposterior base, said sealing ring having a cross-section defining aclosed curve, said closed curve cross section extending substantiallyaround said posterior base, said sealing ring being substantiallyenclosed and defining an inner volume within said sealing ring apartfrom said cavity, wherein said shield is attached to said distal end ofsaid respiratory tube so that said air path in said respiratory tube isin fluid communication with said cavity via said distal end and whereinsaid cavity is in fluid communication with an inner volume of saidsealing ring in a manner to enable said sealing ring to inflate when apressure in said respiratory tube hollow is greater than in said sealingring inner volume and enabling said sealing ring to deflate when apressure in said respiratory tube is lower than in said sealing ringinner volume.
 13. The airway of claim 12, wherein said sealing ring isinflatable at a rate different from other parts of said shield whenpositive pressure is introduced in said shield.
 14. A method ofproviding an artificial airway to a human comprising: placing in thethroat of a human, a supraglottic airway comprising; a respiratory tubehaving a distal end, a proximal end, and a length therebetween, saidrespiratory tube defining a hollow interior; and a shield comprising aposterior base and defining a cavity within the shield above theposterior base, and a sealing ring surrounding said posterior base, saidsealing ring having a cross-section defining a closed curve, said closedcurve cross section extending substantially around said posterior base,said sealing ring being substantially enclosed and defining an innervolume within said sealing ring apart from said cavity, wherein saidshield is attached to said distal end of said respiratory tube and saidcavity and said hollow interior jointly define an air path; attachingsaid proximal end to a ventilation apparatus; and forcing air into saidair path to provide air to said patient; wherein, the act of forcing airinto said air path alters the pressure in said inner volume of saidsealing ring.
 15. The method of claim 14 wherein said alteration ofpressure in said inner volume of said sealing ring comprises alteringthe size of said sealing ring as air is forced into said air path. 16.The method of claim 14 wherein said alteration of pressure in said innervolume of said sealing ring increases the strength of seal of saidsealing ring to said throat.
 17. The method of claim 14 wherein saidalteration of pressure in said inner volume of said sealing ringincreases the pressure said sealing ring imparts on said throat.
 18. Themethod of claim 14, wherein said sealing ring is inflatable relative toother parts of said shield when positive pressure is introduced in saidshield.
 19. An artificial breathing system comprising: a supraglotticairway including; a respiratory tube having a distal end, a proximalend, and a length therebetween, said respiratory tube defining a hollowinterior therethrough; and a shield comprising a posterior base anddefining a cavity within the shield above the posterior base, and asealing ring surrounding said posterior base, said sealing ring having across-section defining a closed curve, said closed curve cross sectionextending substantially around said posterior base, said sealing ringbeing substantially enclosed and defining an inner volume within saidsealing ring apart from said cavity above said posterior base, whereinsaid shield is attached to said distal end of said respiratory tube andsaid cavity and said hollow interior jointly define an air path; and aventilation apparatus designed to increase pressure in said air pathwhich is attached to said proximal end; wherein, when said ventilationapparatus increases pressure in said air path, it also alters thepressure in said inner volume in said sealing ring.
 20. The system ofclaim 19 further comprising a port interconnecting said inner volume ofsaid sealing ring to said cavity, said port allowing said alteration ofsaid pressure in said sealing ring.
 21. The system of claim 20 whereinsaid port comprises multiple holes.
 22. The system of claim 20 whereinsaid port comprises an elongated slit.
 23. The system of claim 19,wherein said sealing ring is inflatable relative to other parts of saidshield when positive pressure is introduced in said shield.